DESCRIPTION: The overall objective of this randomized trial is to test an intervention, delivered in cooperation with a public utility company, intended primarily to change smoking behavior in households where a smoker is present and there are detectable levels of radon. Participants will be identified via stuffers in their utility bill alerting them to the health risks of smoking and radon and inviting them to send for a free radon test kit. Interested households will be randomized into one of two conditions (Usual Care and Enhanced Intervention) when they return their radon test kits. In the Usual Care group, participating households will receive state-of-the-art EPA information on reducing radon in the home. Households in the Enhanced Intervention will receive this EPA information plus special written materials aimed at changing smoking behavior and presenting behavior strategies for changing exposure of family members to radon plus personalized telephone support. The first year of the project will be devoted to identifying and developing effective ways of presenting radon/smoking risk information, refining recruitment procedures, and pilot testing interventions and measures. The second and third years will be devoted to implementing the interventions and conducting the short term evaluation of the study. Year four will include collection of follow-up data, analysis, and development of publications. The effects of the intervention will be evaluated primarily using measures of smoking quit rate and changes in patterns of smoking behavior in the home. Secondary measures of behaviors designed to reduce radon exposure of household members and changes in attitudes and beliefs regarding the link between radon and smoking will also be collected. The long term goal of the study is to develop validated recruitment and intervention procedures that can be used by other public utilities.